1. Field of the Invention
The present invention relates to a method of and apparatus for producing fibrous aggregate.
2. Description of the Related Art
When fibers constituting a fibrous aggregate have small diameters, the fibrous aggregate exhibits various excellent properties, such as filtration properties, liquid retention properties, wiping-off properties, shielding properties, insulating properties, or pliability. Therefore, it is preferable to reduce the diameter of the fibers constituting the fibrous aggregate. Production of the fibrous aggregate composed of fibers having small diameters is carried out by exists a process comprising discharging fiberizable liquid from nozzles, and at the same time, applying an electrical field to the discharged fiberizable liquid to draw the fiberizable liquid, producing fibers having a small diameter, and then directly collecting the fibers to prepare the fibrous aggregate; that is an electrostatic spinning process.
When the fibrous aggregate is produced by a single nozzle in the electrostatic spinning process, the fiberizable liquid is discharged in a small amount, and as a result, productivity is lowered. Thus, methods wherein two or more nozzles are employed to enhance the productivity are proposed. For example, an apparatus for producing a polymeric web, comprising a fiber-forming part for injecting the fiberizable liquid through multi-nozzles composed of plural needles to a collector was proposed (Patent Reference No. 1). A rotating disk device for discharging from two or more discharging holes was also proposed (Patent Reference No. 2). Further, a discharging device which can move across a collector (such as a tube), and a collector which can counter-rotate were disclosed (Patent Reference No. 3).    Patent Reference No. 1: U.S. Pat. No. 6,616,435    Patent Reference No. 2: U.S. Pat. No. 4,650,506    Patent Reference No. 3: U.S. Pat. No. 4,842,505